This application relates to diagnosing and treating conditions which potentially lead to sudden death, normally from cardiorespiratory arrest, in persons who are not otherwise recognized as being at risk for imminent death. One form of this sudden death syndrome is sudden unexpected death in epilepsy (SUDEP). Prevention of SUDEP is complicated by the inability to accurately predict which patients are at risk. Many SUDEP risk factors have been proposed based on demographic parameters (e.g., early onset epilepsy, generalized tonic-clonic seizures, and male sex) and physiological parameters (e.g., heart rate variability and postictal EEG suppression). However, these risk factors have limited predictive value as many patients with low risk profiles still die of SUDEP while some patients with higher risk profiles do not. More reliable methods for determining which persons are at risk for SUDEP would provide significant live-saving benefits.